Time course of oxidative phosphorylation in liver mitochondria of chickens fed on high-protein diet

1. Progressive alterations in oxidative phosphorylation of liver mitodchondria were followed for 14 d in growing chickens fed on either semi-purified low (7%) or high (61%) protein-energy diet. Hepatic mitochondrial oxidative phosphorylation rates were assessed polarographically with pyruvate + malate as substrates. 2. The ADP:O values were reduced significantly 4 d after the feeding of a high-protein-energy diet, when compared with those in chickens fed on a low-protein-energy diet, whereas the state 3 oxidation rates in chickens fed on a high-protein-energy diet from day 6 to 14 were significantly lower than those in low-protein-fed chickens. 3. No changes in sensitivity of mitochondrial ATPase activity to oligomycin, expressed as % of total ATPase activity, were observed among chickens fed for 21 d on diets with various protein concentrations though the FoFi-ATPase activity, expressed per mg protein, tended to decrease in chickens fed on high-protein-energy diet. 4. These results suggest that the reduced ADP:O values for liver mitochondria in the high-protein-fed chickens may not be involved in the degrees of integrity of the FoFi-ATPase.